Electron discharge devices



Dec. 25, 1956 E. c' DENCH ELECTRON DISCHARGE DEVICES Filed Sept. 14, 1953 3 Sheets-Sheet l 5/ l/ANE INSULATION 52 BASE 50 CONDUCTORS 53 I8 37 3 l2 H [B l2 1 38 K 3 /3 46 44 M 19 1776' 2 INVENTO/Z EDWARD C. DENCH TTORNEY Dec. 25, 1956 E. c. DENCH 2,775,721

ELECTRON DISCHARGE DEVICES Filed Sept. 14, 1953 3 Sheets-Sheet 2.1

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INVENTOI? EDWARD C. DENCl-l W W ATTORNEY Dec. 25, 1956 E. c. DENCH ELECTRON DISCHARGE DEVICES Filed Sept. 14, 1953 5 Sheets-Sheet C5 95 "Ki a FE C To INPUT 977 INVENTOR EDWARD C. DENC'H BY J nite 1 ELECTRON DISCHARGE DEVICES Application September 14, 1953, Serial No. 379,770

8 Claims. (Cl. 315-39.3)

This invention relates to electron discharge devices, and more particularly to methods of construction for the frequency responsive elements for such devices designed to operate at relatively low frequencies without unduly increasing the dimensions of the device.

In electron discharge devices of this type, a stream of electrons is directed past or through a series of openings in an anode structure dimensioned in accordance with the operating frequency or band of frequencies. In designing such structures for relatively low frequencies, such as those in the range of 100 to 1000 megacycles, the dimensions of the anode structure are likely to be inconveniently large. In the construction of this invention, lumped constant reactive elements are added to the frequency responsive elements of the anode structure in a manner to produce compact devices of this type capable of operating within this relatively low range of frequencies.

The construction of the invention can be applied to magnetron oscillators of the multicavity type, to traveling wave amplifiers of the type described in the copending application of William C. Brown, Serial No. 81,804, filed March 16, 1949, now Patent No. 2,673,306, dated March 23, 1954, and in the copending application of the applicant, Serial No. 268,097, filed January 24, 1952, in which a stream of electrons is directed by a magnetic field past a series of frequently responsive elements in an anode structure. The principles of this invention may also be applied to amplifiers of this type in which a stream of electrons is directed by an electrostatic field through a series of annular electrodes.

The foregoing and other advantages, objects and features of this invention will be better understood from the following description taken in conjunction with the accompanying drawings in which:

Fig. 1 is a horizontal sectional view of an embodiment of the invention in a magnetron traveling wave type of amplifier;

Fig. 2 is a section along the line 22 of Fig. 1;

Fig. 3 is an enlarged view of a portion of the anode ring showing the attachment of a Vane to the anode ring;

Fig. 4 is a schematic diagram of the delay line of Fig. 1;

Fig. 5 is the equivalent circuit of the delay line shown in Fig. 4 as used in a backward wave oscillator;

Fig. 6 is another embodiment of the invention as applied to a magnetron type oscillator;

Fig. 7 is a longitudinal section of another embodiment of the invention;

Fig. 8 is a top view of the embodiment of the invention shown in Fig. 7; and

Fig. 9 is a schematic diagram of the delay line of Fig. 8.

In Figs. 1 and 2 there is shown an amplifier of the magnetron type which comprises an anode structure 10 consisting of a ring 11 supported in an outer ring 12 by an annular disc 13. The ends of the outer ring 12 are States Patent 0 2,775,721 Patented Dec. 25, 1956 closed by an upper pole piece assembly 14 and a lower pole piece assembly 15, thereby forming a closed cylindrical container. This container structure may be made of any good electrical and heat-conducting material, for example, copper.

The upper pole piece 14 is formed with a circular opening at the center thereof through which extends a supporting means 16 for a cathode 17. The cathode shown is of the indirectly-heated type wherein a coil is wound inside a cylinder, the outside of the cylinder being coated with an electron emissive material. The ends of the cathode cylinder 17 are covered by discs 18 which are slightly larger in diameter than the cylinder of the cathode 17 and which act as heat shields and as electron space charge shields. The details of construction of such a cathode support 16 and the connectors are well known. Another opening is formed in the center of the lower pole piece through which an exhaust tubulation 19 is mounted and sealed in any convenient manner. The anode structure 10 is formed with a plurality of vanes 20 extending inwardly from the ring 11 to points on a circle adjacent the cathode 17 and concentric with its axis. These vanes 20 are flat rectangular metallic structures, the main planes of which are radial to the axis of-the ring 11. The space between the inner ends of these vanes and the cathode structure 17 constitutes an electron interaction space for the operation of the device.

The vanes extend around the cathode over substantially its entire circumference. However, in one region a few of the vanes have been omitted. The vanes bordering on this gap constitute the input and output ends, respectively, of the anode transmission line structure.

The input and output ends are coupled to their respective loads, which are preferably impedance matched to the anode transmission line, by coaxial connectors 21 and 22. Each of these connectors comprises an outer cylindrical member 23 or 24 attached to the walls of an opening in the outer ring 12 adjacent to the end of the anode vane transmission line structure that is to be coupled to said lead. The member 23 or 24 which is hollow contains therein a central member 25 or 26 insulatedly supported therefrom by a glass sleeve 27 or 28 attached to the central member 25 or 26. The central conductor 25 or 26 is connected to a vane 20 near the cathode end. The other conductor 23 or 24 is attached to the anode ring 12 representative of ground potential at radio frequency. Between the input and output coupling devices there is a member 30 comprising a copper block extending inwardly from the anode ring 12 to a position in close proximity to the cathode 17 Where it serves to prevent the recycling of the electron stream.

Vanes 20 and the separating member 30 are attached to the anode ring 11 by screws 32 but insulated from it by washers 33 and 34 of insulating material. In addition, adjacent vanes 20 are connected by tubular loops 35 of conductive material. The tubular passages 36, formed within the loops 35, are connected to a source of cooling fluid through tubes 37 and 38 supported in openings 40 and 41 formed in the outer ring 12 by vacuum-tight bellows 42 and 43.

The transverse magnetic field required in this type of device to direct the stream of electrons through the interaction space between the anode 10 and the cathode 17 is provided by a permanent magnet 44, only part of which is shown in Fig. 2, to which the pole pieces 14 and 15 are attached. These pole pieces 14 and 15 .are fed into openings in the top 45 and the bottom 46 of the cylindrical container. The resulting transmission line is shown diagrammatically in Fig. 4. The ring 53 11 is represented by the rectangle 50. The vanes are represented by the rectangles 51 and are shown separated from the ring by insulated washers 52. The loops 35 are represented by conductors 53.

This structure can be connected as a backward wave oscillator, as shown in the schematic diagram of Fig. 5, in which an electron beam 54 originates at a cathode 55 and proceeds under the influence of an accelerating potential and a transverse magnetic field past vanes 56. These vanes are connected by coils 57 representing the inductance of the loops 35 of Figs. 1 and 2. The capacitors 69 in this diagram represent the capacity of the capacitors formed between the vanes 20 and the anode ring 11 separated by the insulated washers 33. The vanes 56 are connected to a source 61 of positive potential through the inductances 57 and an inductance 62 of half the value of the inductances 57 and also through an inductance 63 of considerably greater value. The transmission line formed by the inductances 5'7 and the capacitors 69 is terminated by a resistor 64 of a resistance equal to the characteristic impedance of the line. The other end of the line is connected to output terminals 65 and 66 through a coil 67 equal in inductance to half the inductance of each coil 57 and through capacitors 68 and 70. The result is a backward wave oscillator capable of operating at a relatively low frequency and yet of a compact construction. The operation of a backward wave oscillator is described in applicants co-pending application, Serial No. 372,522, filed August 5, 1953.

The tuning structure of the invention may be used with a magnetron oscillator, as shown in Fig. 6. As in the structure shown in Fig. 2, there is an anode structure 71 consisting of a ring 72 supported in an outer ring 73 by an annular disc 74. The ends of the outer ring are closed by plates supporting pole piece assemblies in a manner similar to that shown in Fig. 2 to form a closed cylindrical container of conductive material. The anode 71 is shown with the top cover removed.

A cathode 75, which may be of the same type of construction as that of the cathode 17, shown in Figs. 1 and 2, is positioned at the center of the ring 72. The anode structure 7i is formed at a plurality of vanes 76 extending inwardly from the ring '72 to a line adjacent the cathode 75 with the space between constituting an electron interaction space for the operation of the device. An output coupling device '77 is inserted into one of the cavities formed between two vanes 76. This coupling device can be constructed in any or several well-known ways. The vanes 76 are attached to, but insulated from, v

the ring 72 in the same manner as the vanes 20 in Fig. l. The adjacent vanes 76 are connected by loops 78. These loops may also be made hollow for cooling purposes. A transverse magnetic field is applied to the interaction space by the same type of permanent magnet and pole pieces as shown in Fig. 2. The equivalent circuit for the anode structure of this embodiment is the same as that shown in Fig. 4.

Figs. 7 and 8 show a linear amplifier embodying the invention with lumped inductances and capacitors added in a more conventional form and connected in a different circuit than that shown in Fig. 5. In such a tube, a box is formed with metal plates for the top 80 and the bottom 81. Vanes 82 are mounted on the top plate 80, perpendicular to that plate, insulated therefrom and parallel to each other to form a series of cavities between adjacent vanes and the plate 80. A cathode 83 is mounted in the lower plate 81 immediately below the two vanes on the left, as seen in Fig. 7. A collector electrode is mounted in the right-hand end of the plate 81, as seen in Fig. 7, and connected to a source of positive potential. A magnetic field is applied to cause electrons emitted from the cathode 83 to flow past the lower ends of the vanes 82 to the collector 84. A trough is mounted below the lower ends of the vanes 82 to con 4 fine the beam of electrons from the cathodc 33; to the collector 84 to the interaction space. The trough 85 is supported and connected to a source of potential by an insulated support 86.

Studs 92 are formed on the upper ends of the vanes 82 at alternate sides and pass through openings in the top plate 80 to which they are afiixed by vitreous material. The studs 92 form terminals to which an external circuit is connected, as seen in Fig. 8. This circuit is shown in schematic form in Fig. 9. Adjacent studs 92 are connected through parallel resonant circuits, each comprising a capacitor 93 and an inductor 94. A plate 95 is mounted on the upper plate 80 by standoffs Coils 97 are mounted on the underside of this plate 95 by screws 98 and nuts 100. The coils are connected between alternate studs 92 in two sets with the end coils of the lower set each having half the inductance of the main coils. Resistances may be added to this circuit to increase its ohmic resistance. The vanes 92 are connected to a source of positive potential through radio frequency chokes 102 and 103 and coils 97. The radio frequency energy is inserted through capacitors 164 and 105 and taken oft through the coils 97 after amplification.

The invention may be used with strapped anode structures. Lumped impedanccs may be added to anode structures of the interdigital type in the manner of the invention. It is to be understood that, when the structure of Figs. 1 and 2 is used as an amplifier as shown, inputs and outputs must be provided as shown in Fig. 9. Similarly, the structure of Fig. 7 may be used as an oscillator if properly terminated as shown in Fig. 5.

This invention is not limited to the particular details of construction, materials and processes described, as many equivalents will suggest themselves to those skilled in the art. It is, accordingly, desired that the appended claims be given a broad interpretation commensurate with the scope of the invention within the art.

What is claimed is:

1. An electron discharge device comprising a cathode, an anode structure comprising a supporting member, vanes attached to but insulated from said supporting member, each pair of vanes together with that portion of said supporting member lying therebetween comprising a frequency responsive element, conductors joining adjacent vanes and means for inserting radio frequency energy at a range of frequencies not including the resonant frequency of the frequency responsive elements near one end of said structure, and means for extracting radio frequency energy from said structure.

2. An electron discharge device comprising a cathode, an anode structure comprising a supporting member, vanes attached to but insulated from said supporting member and having openings therein, each pair of vanes; together with that portion of said supporting member lying therebetween comprising a frequency responsive element, hollow conductors joining adjacent vanes, means for passing cooling fluid through said vanes and conductors, means for inserting radio frequency energy at a range of frequencies not including the resonant frequency of the frequency responsive elements near one end of said structure, and means for extracting radio frequency energy from said structure.

3. An electron discharge device comprising a cathode, an anode structure comprising a supporting member, vanes attached to but insulated from said supporting member, each pair of vanes together with that portion of said supporting member lying therebetween comprising a frequency responsive element, an impedance connected externally between adjacent vanes, means for inserting radio frequency energy at a range of frequencies not including the resonant frequency of the frequency responsive elements near one end of said structure, means for extracting radio frequency energy from said structure, and means for producing a magnetic flux in a direction at right angles to a plane including the openings to the frequency responsive elements.

4. An electron discharge device comprising a cathode, an anode structure comprising a supporting member, vanes attached to but insulated from said supporting member and having openings therein, each pair of vanes together with that portion of said supporting member lying therebetween comprising a frequency responsive element, hollow conductors connecting adjacent vanes, means for passing cooling fluid through said vanes and conductors, means for inserting radio frequency energy at a range of frequencies not including the resonant frequency of the frequency responsive elements near one end of said structure, means for extracting radio frequency energy from said structure, and means for producing a magnetic flux in a direction at right angles to a plane including the openings to the frequency responsive elements.

5. An electron discharge device comprising a cathode, an anode structure comprising an arcuate supporting member concentric with said cathode, vanes attached to but insulated from said supporting member, each pair of vanes together with that portion of said supporting member 'lying therebetween comprising a frequency responsive element, an impedance connected externally between adjacent vanes, means for inserting radio frequency energy at a range of frequencies not including the resonant frequency of the frequency responsive elements near one end of said structure, and means for extracting radio frequency energy from said structure.

6. An electron discharge device comprising a cathode, an anode structure comprising an arcuate supporting member concentric with said cathode, vanes attached to but insulated from said supporting member, each pair of vanes together with that portion of said supporting member lying therebetween comprising a frequency responsive element, conductors joining adjacent vanes, means for inserting radio frequency energy at a range of frequencies not including the resonant frequency of the frequency responsive element near one end of said structure, means for extracting radio frequency energy from said structure, and means for producing a magnetic flux in a direction at right angles to the plane of said circle.

7. An electron discharge device comprising a cathode, an anode structure comprising an arcuate supporitng member concentric with said cathode, vanes attached to but insulated from said supporting member and having openings therein, each pair of vanes together with that portion of said supporting member lying therebetween comprising a frequency responsive element, hollow conductors joining adjacent vanes, means for passing cooling fluid through said vanes and conductors, means for inserting radio frequency energy at a range of frequencies not including the resonant frequency of the frequency responsive element near one end of said structure, means for extracting radio frequency energy from said structure, and means for producing a magnetic flux in a direction at right angles to the plane of said circle.

8. An electron discharge device comprising a cathode, an anode structure comprising a supporting member, vanes attached to but insulated from said supporting member, each pair of vanes together with that portion of said supporting member lying therebetween comprising a frequency responsive element, an inductance connected.

between each pair of alternate vanes, a lumped constant parallel resonant circuit connected between adjoining vanes to form a transmission line and a resistor of the characteristic resistance of the transmission line connected between the two sets of inductances, and means for extracting radio frequency energy from said structure.

References Cited in the file of this patent UNITED STATES PATENTS 2,474,898 Heising July 5, 1949 2,480,126 Frankel Aug. 30, 1949 2,502,405 Brown Mar. 28, 1950 2,504,894 Sloan Apr. 18, 1950 2,546,773 Nelson Mar. 27, 1951 

